It is known that industry and document reproduction providers, for example, use large-format paper webs, in particular printed paper webs, to record technical documentation or other comprehensive data records thereupon. The standard widths of such paper webs range up to 914 millimeters (36″). The length of the paper web—and thus that of the document—can vary and can measure up to 100+ meters depending on application.
It is also known that large-format documents of this type are folded for easier handling or archiving. In Germany, standardized folding of technical documents is regulated in DIN 824. Folding standards vary by country.
Paper-folding of this type is usually as automated as possible, with folding machines being able to handle both lengthwise and widthwise folding and using rollers or belts, for example, for folding.
In this case, however, the length of the paper web to be folded one time, and thus the size of the documents being processed once are subject to technical limits. Because of this, the process of folding the printed paper web results in the formation of stacks of pages folded one-over-the-other that must be transported by components (for example rollers, folding belts) of the folding machine. These components must therefore be movable so that they provide the required space. The mobility of these components, however, compromises the accuracy of the folding. The folding length, i.e. the total width of the folded pages, is thus limited to approximately 6 m on roller-based folding machine when using 80 g/m2 weight paper. With a belt-based folding machine, the folding length for such paper would be limited to approximately 12 m. In both cases, the costs would rise disproportionately as folding length increases.
To be able to achieve large folding lengths for paper webs of several tens of meters to over one hundred meters, however, semiautomatic methods are designed, for example, such that stacks are initially folded to the maximum possible paper length and then moved from the folding machine into a storage position. The paper web remains connected to a further portion of the paper web via an unfolded trailing sheet, and a section of this trailing sheet serves as the basis for an additional subsequent stack of continuous sheets to be folded thereupon. This subsequent stack can then also be built up to the technologically possible length and then discharged. This method can be continued over multiple stacks. This results in a product of at least a few automatically generated folding packages that are connected to one another via unfolded trailing sheets. These trailing sheets must then be manually refolded by a system operator so that the individual folding stacks can be set one on the other to form a large stack. This manual folding of the trailing sheets is time-consuming, labor-intense and involves a high rate of failure.
DE 10 2009 032 159 discloses a fully automatic folding machine and a folding method in which an unfolded portion must be outputted when a paper stack is deposited in a tray and then retracted into the folding machine with at least a portion of the folded layers following the depositing of the paper stack so that these areas can be used as the basis for a folding stack. This comparatively large retracted portion of the paper can subsequently cause folding inaccuracies and delays in the folding procedure.
WO 2010/018059 [U.S. Pat. No. 8,298,127] also discloses a fully automatic folding method in which the paper is held back in the folding station while the folded stack is moved into the tray. During this time, the paper supply to the folding station must be stopped. Because, however, the upstream device, for example a printer or plotter or similar continuously operates, this results in a large loop of paper that must be handled when the subsequent stack is created.